Emperor Taizong of Tang

Emperor Taizong of Tang (28 January 598-10 July 649) was Emperor of Tang China from 4 September 626 to 10 July 649, succeeding Emperor Gaozu and preceding Emperor Gaozong. He was one of China's greatest rulers, reforming the legal system, decreasing corruption, and conquering Central Asia.

Early life
Li Shimin was born in Wugong, Sui China in 598 AD, the son of Li Yuan. His name meant "save the earth and pacify the people", as his father was told that his son had the features of both the dragon and the phoenix and that he could bring the empire into prosperity by the age of 20. Li Shimin received the best Confucian education and training in archery and horsemanship, and, in 613, Gao Shilian gave his 12-year-old niece in marriage to the 14-year-old Taizong. Two years later, Li Shimin served with distinction as the commander of a military force which rescued the Sui emperor from encirclement by the Gokturks, and he was chosen above his other brothers to accompany his father to Taiyuan in 616 AD when his father became governor.

Rise to power
During the disintegration of the Sui dynasty due to agrarian revolts, Li Shimin advised his father to rise in rebellion against the Sui, and, when Li Yuan hesitated, Li Shimin proclaimed that the uprising was good for the realm and stated that, "Retreating to Taiyuan, we are nothing but a rebel force, but advancing to Chang'an we could command people within the realm." Li Yuan was persuaded to advance to the capital, where he founded the Tang dynasty in 618 AD. Li Shimin won four major battles and several smaller skirmishes against the other warlords of China, with his greatest victory being located at the Battle of Hulao (near the former capital of Luoyang), where he defeated Dou Jiande and Wang Shichong. Shimin's rise to power upset his older brother Li Jiancheng, and factions began to form around the rival brothers. In 626 AD, Li Shimin's younger brother Li Yuanji was given control of Li Shimin's former army and sent to fight the Gokturks, and Li Shimin, upset with his loss of military support, plotted a coup. He spread a rumor to his father that his brothers were committing adultery with their father's concubines, forcing the brothers to return to Chang'an. There, at Xuanwu Gate, Li Shimin ambushed personally killed Li Jiancheng with an arrow, while a subordinate killed Li Yuanji. Li Shimin then led his troops into the Imperial Palace and forced his father to abdicate in his favor, becoming Emperor Taizong.

Reign
Taizong appointed his brother Jiancheng's former advisor Wei Zheng as one of his own senior advisors, and he immediately set about reforming the new dynasty, which suffered from a swolled nobility and an inflated number of prefectures and counties, so he sent Fang Xuanling to reduce the number of military and civil posts across the country. He curbed corruption by publicly shaming corrupt officials, and he ordered that the severities of penalties for certain crimes be reduced (replacing the amputation of feet with banishment). In 633 AD, he ordered that men condemned to death would only be executed if the issue was presented to him on three separate occasions, preventing hasty executions.

Taizong then focused on expanding his empire's dominions, having previously used marriage and internal subversion to pacify his neighbors as the Tang economy strengthened. In 626 AD, when the Eastern Turkic Khaganate invaded Shanxi with 100,000 nomadic cavalry and reached within ten miles of the capital, the Turks were bribed to retreat. In 627 and 628, when the Eastern Turks suffered a number of tribal revolts, they were devastated, and Jiali Khan sent his nephew Tuli to repel the rebels. When Tuli was defeated, Jiali had him flogged and imprisoned for ten days, so Tuli fled to Taizong and successfully enlisted his help in fighting his uncle. Tuli's faction became vassals of the Tang, so Taizong sent 100,000 Chinese troops to subdue the Gokturks, defeating and eventually capturing Jiali, who was sent to Chang'an as a political hostage. The remaining Turkic chieftains then had Taizong assume the mantle of "Tengri Khagan", ruling over the Turkic tribes of Central Asia and gaining the right to mediate in disputes. Taizong agreed, and 100,000 Turks were then distributed among the Chinese frontier from Hebei to Shanxi and 10,000 tribal aristocrats came to live in Chang'an. Taizong then employed the same tactics against the Western Turkic Khaganate, and he also conquered the wealthy Silk Road cities of the Tarim Basin in 640 AD. The Tibetans were then pacified by marriage alliance. In 645 AD, Taizong personally led an invasion of Goguryeo which failed due to winter attrition; in 647 and 648, other invasions of Goguryeo failed. At the same time, the Koreans asked the Turkic Xueyantuo tribe to ally with them against Taizong. The Xueyantuo leader Duomi Khan was quickly defeated by Taizong, and many more chieftains came to Taizong asked him to become their Khagan; Taizong established another protectorate in 646.

However, Taizong had taken ill during his Korean campaign, and his son Li Zhi became his regent. Taizong called in an Indian magician to help him, and he wrote four chapters to instruct his son on how to rule. On 10 July 649 AD, Taizong passed away in Chang'an. His reign was a high water mark for Chinese history, as he left his son with a massive empire, a strong economy, and a solid administration.